Geocells (also known as cellular confinement systems) are a three-dimensional geosynthetic product which are useful in applications such as soil erosion prevention, channel lining, construction of reinforced soil retaining walls, and support of pavements. The geocell was originally designed by the United States Army Corps of Engineers (ACE) for fast deployment of troops on sandy dunes which generally could not support the load of heavy vehicles (e.g. trucks, tanks, etc).
As described in U.S. Pat. No. 4,797,026, the geocell as contemplated for military applications was made of several strips of high density polyethylene (HDPE), with each strip having a wall thickness of 1.27 mm (0.05 inches). The strips were welded together in an offset manner by ultrasonic welder, with the distance between welded seams being 330 mm or greater.
The construction of geocells has not changed much in these basic characteristics in the last few decades. Geocells are manufactured today by many tens of manufacturers along the world. The vast majority of geocells are still made of HDPE, with a very few being made of polypropylene (PP). The usual strip wall thickness is 1.27 millimeters, with a few variations in the range of 1.0 mm to 1.7 mm. The cell walls are frequently perforated and embossed; see for example U.S. Pat. Nos. 6,296,924; 6,395,372; and 4965097; and U.S. Patent Pub. No. 2006/0147276. Some manufacturers vary their cells slightly either by changing the perforation pattern or by offering larger cells (i.e. the distance between seams is greater than 330 mm). Regardless of these variations, the original cell wall thickness originated by the ACE has not changed and is always, without exception, by all manufacturers in the range of 1.0 mm to 1.7 mm, so that the geocell has a wall strength of from 15,000 to 23,000 N/m (Newton per meter), respectively.
During the last few decades, some additional geotechnical applications of the original geocell design have been developed, for example the use of geocells in slope soil stabilization (mainly for erosion control), retaining walls, channel protection (mainly for erosion control), temporary pavements, or light duty pavements. However, the design of the geocell has not been changed or optimized for each new application. Because the original geocell design has not been changed and is not optimized, the relatively high cost of product, cost of shipment and cost of installation are limiting factors in expanding the use of goecells and increasing the market size for such products.
It would be desirable to provide geocells that meet relevant engineering requirements such as strip strength, seam strength, and sufficient vertical stability and stiffness to survive possible installation damage during the in-situ infilling process, yet are lower in cost, easier to install, and do not present sheer waste due to over-design.